1. Field of the Invention
The present invention relates to a charging method and a charging structure of a combustible gas and an oxdizer gas, as well as a material to be charged by using the charging method and the charging structure.
2. Description of the Related Art
As is disclosed in Japanese Patent Application Laid-open No. 5-278554, a gas generating apparatus for an air bag apparatus contains in its high-pressure container a combustible gas mixture for inflating the air bag. The high-pressure container is formed at its one end wall surface with an opening to which a cap is mounted. The cap is provided with a passage through which various gases are charged into the high-pressure container under a predetermined pressure. After the various gases are charged into the high-pressure container, the passage of the cap is sealed.
Such a combustible gas mixture is prepared by mixing the combustible gas and the oxdizer gas at certain composition for burning. A lower limit and an upper limit of the composition of the combustible gas which is required for burning are called a flammable lower limit and a flammable upper limit, respectively. And a range between these flammable lower and upper limits is called a flammable range or a combustion range. Further, a minimum igniting energy of each of the combustible and oxdizer gases with the flammable range is 0.02 mj (milli joule) if a hydrogen is used as the combustible gas and an oxygen is used as the oxdizer gas.
When a gas is charged into the high-pressure container under pressure, the gas temperature is increased by heat generated due to compression of the gas. When the combustible and oxdizer gases are charged, if the gas temperature reaches a temperature of a spontaneous combustion (400.degree. C. or higher in the case of hydrogen), the gas unintentionally starts burning even if there is no igniting source.
That is, in a gas generating apparatus for an air bag apparatus, when the combustible and oxdizer gases are charged into the high-pressure container and the charging port is sealed, it is desired to take such characteristics of the gases into consideration, and to establish a sufficiently practical charging technique.